1. Field of the Invention
The present invention relates to the generation of electrical power from submerged generators using water currents to turn the generators, and in particular, the surface area profile of the rotor blade used on the generators.
2. Description of the Prior Art
Waves are created by winds blowing over large bodies of water; tidal changes in the sea are generated by solar and lunar gravitational forces. As the earth rotates the elliptical envelope shape of the ocean floor causes the water level to rise and fall. Ocean waves and tides contain tremendous amounts of kinetic energy which can be harnessed to turn generators for the production of electricity. Water is several hundred times denser than air, therefore, has more kinetic energy per unit speed. Submersible generators harness the kinetic energy to turn the generators.
The eastward rotation of the Earth generates the winds which cause the waves; the Gulf Stream and the Kuroshio are two natural currents resulting from the Earth's rotation. The Gulf Stream starts just south of the Florida Keys and continues north for about 400 miles. The current has an average speed between 4-7 miles per hour depending on width. So long as the Earth rotates eastward, there will be winds generating waves and currents. Tidal changes result from lunar and solar gravitational forces. This enormous power, if appropriately harnessed, is fuel that is cost-free, non-polluting, and self-sustaining. Tidal currents are predictable for the years in advance; wave patterns are predictable for days in advance. Predictability is an important characteristic for an energy source used in electricity generated for input into an electric grid where the supply equals demand.
The present disclosure is concerned with harnessing tidal power which is generated by lunar and solar gravitational forces as the Earth rotates eastward. It could be adapted for the more powerful currents occurring in the Gulf Stream which are caused by winds, uneven temperatures, and the shape of existing land masses. Tidal currents are the periodic motion of water caused by the different lunar and solar gravitational attractive forces on different parts of the eastward rotating Earth. As these gravitational forces change, tides rise and fall causing periodic horizontal movement of water, the tidal currents. The tidal current speed varies from place to place depending on the shape of the coastline being strongest in inlets, sounds, coastal waterways, and related. Since the amount of electricity generated depends on the speed and steadiness of the water driving the generating device, the tidal currents can produce electricity only between high tides and low tides.
The extraction of kinetic energy from flowing water is an extremely complex operation and several devices have been tested. The most common are horizontal-axis devices in which the axis of rotation of the rotor is horizontal with respect to the ground and parallel to the energy stream. Generators are well known in the prior art, several models are available commercially which are usable in either wind or water provided the water unit has a water-proof housing. The kinetic energy of the water turns a rotor blade which is attached to a rotor shaft which extends into the generator. A series of step-up gears increase the rotational speed such that electricity is generated.
The rotor blades used on wind turbines tend to be long and narrow since this design is easier to secure during violent wind storms. The long and narrow rotor blade design has been tested with water turbine systems, but has encountered several problems. The two major problems are injury to fish and other marine species, and the blades can be damaged by seaweed and other submerged debris in the water. The long, sweeping motion of the rotor blades tend to attract fish and injure them as they swim by in the sweep path of the rotor blades. In addition, these blades tend to collect and retain seaweed and other debris which cause structural damage.
U.S. Pat. No. 6,302,652, issued to John Roberts, and US application 2008/0138206, Dean Corren inventor, relate to curved rotor blades.
The above references fail to at least teach or suggest the design of the presently disclosed and claimed invention.